But, to my disappointment, the memory usage that is measured is determined by "Memory Usage" column of Windows Task Manager. It is NOT the correct method of measuring memory usage, because it only indicated how much memory is "active", not the total memory allocated by the program. To get how much memory allocated, the correct column is "VM Size" in XP or "Commit Charge" in Vista. Actually programs such as TaskInfo are able to reduce the "Memory Usage" of any program (e.g. 5 MB only for Firefox 2). Hence, "Memory Usage" is not a good measure for memory usage.

So, I ran a test of Firefox 2, Firefox 3 beta 1, Opera 9, and Internet Explorer 7 to see the real memory usage. As a bonus, Javascript speed test is added from Celtic Kane.

I ran all the test in an almost-clean Windows XP installation. Firefox's profile directory were set differently for Firefox 2 and 3. Screenshots with Task Manager open are always available :) No plug-ins (even flash) or extensions were installed!

Step 0 - install

Firefox 2

Firefox 3

Opera 9

IE 7

Installer name

Firefox Setup 2.0.0.9.exe

Firefox Setup 3.0 Beta 1.exe

Opera_9.24_Eng­ _Setup.exe

IE7-WindowsXP­ -x86-enu.exe

Installer size

5.74 MB

6.40 MB

4.69 MB

14.7 MB

Installed size

19.9 MB

22.8 MB

4.81 MB (yeah!)

Who knows?

Step 1 - blank

I set the browser's start-up page to be blank. Then I started the browser and here are the memory usage.

Firefox 2

Firefox 3

Opera 9

IE 7

VM Usage

11,672 KB

13,076 KB

12,568 KB

11,616 KB

Screenshot

IE is the best for blank page (HEHE)

Step 2 - Google only

I opened www.google.com which redirected me to www.google.com.sg since I am currently in Singapore.

Firefox 2

Firefox 3

Opera 9

IE 7

VM Usage

12,152 KB

13,432 KB

14,056 KB

15,128 KB

Screenshot

Here we can see the worseness of IE starts to appear.

Step 3 - Digg only

Why Digg? Because it is loaded with lots of Javascript.

Firefox 2

Firefox 3

Opera 9

IE 7

VM Usage

18,700 KB

22,280 KB

19,780 KB

30,920 KB

Screenshot

I am quite disappointed knowing that Firefox 3 is not better in terms of memory usage than Firefox 2. IE? WOW.

Step 4 - open 7 and 12 sites and a digg page

I tried to open 7 sites below:

www.yahoo.com

www.cnn.com

www.opera.com

www.firefox.com

www.netcraft.com

www.slashdot.org

www.amazon.com

After all are loaded, I clicked on each of the 7 tabs two times to let the browser actually draw the page elements on screen. Then I opened 5 more sites below and clicked each of them again.

www.bbc.co.uk

www.detik.com

www.kompas.com

www.cnet.com

www.kejut.com

I added one more, which is the digg page for the ZDNet's memory test, but this time I clicked the "Expand Tree" to make the page very long and Javascript-intensive.

I calculated the difference in memory usage before and after opening the last page.

Firefox 2

Firefox 3

Opera 9

IE 7

After 7 sites

40,556 KB

45,320 KB

44,284 KB

71,120 KB

Screenshot

After 12 sites

59,648 KB

59,068 KB

65,492 KB

99,936 KB

Screenshot

After add last page

73,540 KB

73,244 KB

75,800 KB

119,748 KB

Increase in memory

13,892 KB

14,176 KB

10,308 KB

19,812 KB

Screenshot

Only after opening 12 pages then Firefox 3 uses less memory than Firefox 2? I wonder why. Opera has the lowest increase of memory when opening the last page. I think because Opera is still very efficient in the Javascript processing.

Step 5 - clean up

After the previous step, I closed all the 12 tabs, and I set the last tab to about:blank. I wanted to know how much the browsers clean up the memory. Result:

Firefox 2

Firefox 3

Opera 9

IE 7

VM Usage

46,952 KB

55,936 KB

61,588 KB

56,860 KB

Screenshot

I hoped this was the best thing in Firefox 3, but my hope was wrong! Firefox 3 still consumed much more memory than Firefox 2. WHY? I don't know. Opera, as I expected, still used much memory, because I can click the trash-can and open closed tab, and the opening will be very fast, looks like the pages are still in memory.

Bonus - Javascript speed test

I wondered, did the Firefox developers made Javascript execution faster in Firefox 3? At least I can be proud of it if they did. So I used the test from Celtic Kane to measure it.

Firefox 2

Firefox 3

Opera 9

IE 7

VM Usage

15,520 KB

16,696 KB

15,920 KB

22,392 KB

Total Duration

1832 ms

2974 ms

931 ms

1262 ms

Relative to Opera

1.97 times

3.19 times

1.00 times

1.36 times

Screenshot

Nothing interesting about the memory usage... but !? how come Firefox 3 is very slow? I tried not only once, but more than five times and it was still about the same.

Conclusions

Firefox 3 does not uses less memory than Firefox 2. It also does not clear unused memory when all the pages are closed. However, both Firefox 2 and 3 are still conservative compared to IE 7. It is surprising that Firefox 3 is significantly slower in Javascript execution than Firefox 2.

Opera uses slightly more memory than Firefox, and IE is really a memory hog. When switching tabs I needed to wait about ~0.4 seconds in IE but it was instant in Firefox and Opera.

I still have the test machine unmodified by this time, if anyone want to suggest a test that would be better reflects the better memory management of Firefox 3, please write down below. Suggestions and comments are happily welcomed! ↓

Interesting. Thanks.
The web pages you (And Adrian Kingsley-Hughes) used for your
tests both serve up ads. These ads can be different each
time the page is downloaded or refreshed. In step 3 above,
the Opera page is clearly showing a different ad. There must
be some variation in the size of ads served up- a Flash
animation will be much larger than a simple banner. How much
does this variation in ad size affect the result, I wonder?

Donald [gb], 24 Nov 2007, 8:44 reply

Hi! Thanks for your comment.
Different images for the ads surely affects memory usage,
but I think it is not significant, since a banner is about
10-20 KB only. Regarding the Flash, all the browser here are
tested without Flash plug-ins, so no Flash file can run :D

yuku [sg], 25 Nov 2007, 14:27 reply

Interesting. Thanks.
Hope you can add safari in for the benchmark. (Konqueror and
Nautilus also ^^)

imam [sg], 24 Nov 2007, 19:04 reply

setuju.. tambahin safari donk.. =)

emka [sg], 9 Dec 2007, 19:58 reply

good review...

yosafat [sg], 26 Nov 2007, 14:12 reply

Im my humble experience FF is a complete memory hog compared
to IE. Not sure what you are doing wrong but IE is faster
and trimmer.

donkeywonkey [us], 27 Nov 2007, 13:15 reply

From your comment I saw that you are using IE 6.
IE 6 uses much less memory than IE 7. Although I have not
tested it formally, IE 6 uses about half the memory used by
IE 7. IE 6 may use less memory than FF.

yuku [sg], 27 Nov 2007, 13:25 reply

IE 6 doesn't have tabs :O

ryan [us], 23 May 2008, 17:59 reply

very good thanks!!

stirner [it], 29 Nov 2007, 16:40 reply

On Windows 2000 at least, the VM number may be either
greater or smaller than the Memory Usage number. Processes
like Outlook with many windows open but minimized can have
VM twice the size of Memory Usage, while the System Idle
process shows only Memory Usage (16k) with 0 VM.
This leads me to believe that the actual correct measure of
total allocated memory is the sum of the two. And the
distribution between the two can affect how that process
influences or is influenced by memory swapping of other
processes. The PageFaults number is a measure of the amount
of swapping in and out of Virtual Memory the process has
done since startup.
The Commit Charge number may be more like a total, but I
cannot say authoritatively on that.

agreed, VM (virtual memory) never seems to be included in
memory usage of programs when this is clearly important,
sometimes the physical memory usage is much lower than the
VM usage. surely an improvement to the tests would be to
give VM usage and or a total memory usage and maybe an
accumulative memory used when leaving the browser open or is
that the same as the memory clean up?
Firefox 2.0.0.11

Edox [eu], 26 Jan 2008, 14:33 reply

nice comparison. i think people should stick with IE6 if PC
is lowsy 1

danny how chung [my], 6 Feb 2008, 7:41 reply

weh,., nice comparisson... thank ya...

budi pasadena [id], 26 Feb 2008, 8:12 reply

I wonder how Maxthon would compare? While it uses IE's
rendering engine, that does *not* mean it will perform
similarly to IE. I could use the engine from a Chevy truck
in a boat, and obviously those two vehicles would have very
different usage statistics. I use it (on top of IE6, can't
find a reason to switch to IE7) and find it consistently
uses much less memory than FF 2. And for some reason, after
a few hours usage I have to restart FF because of it's
memory and pagefile usage, sometimes above 350MB for each
(and I only have 512MB RAM/1024 pagefile)!
I'm a webpage developer, and do a lot of JavaScript stuff,
so that might account for part of it. Anyways, this is a
great article. Thanks!

TedInAK [us], 6 Mar 2008, 0:23 reply

This is a very good article. I've been using Opera for a
while now. I don't know how memory efficient it is, but it
definitely feels much faster than Firefox.
Only problem is some Javascript (which is browser
dependent), so I have to use Firefox now and then. Forget
about IE ! hehe ..
Again , good article !

mr jp [au], 17 Mar 2008, 22:15 reply

well done tests, but the first beta of FF3 was still not
optimized, which could explain the high memory consumption
and speed drop. Try beta 3 or 4, and the performance gains
should be significative.

mr m [cl], 18 Mar 2008, 13:03 reply

super article thanks you administrator

turkey [tr], 19 May 2008, 8:58 reply

ini yg sy cari ^^ T.O.P B.G.T

randy [id], 15 Jun 2008, 2:33 reply

Great article. Thanks for the effort. Don't really see need
to to change from IE6 on my old Latitude 600! Just get more
memory. Less disruption.

thanks for this review ,
what i see from it that opera9 is almost the best?
the newer version (9.51) is thicker and slower and take 2
much mem usage but still better than ie and firefox3 but
forefox 2 is the best

unknown [qa], 14 Jul 2008, 15:53 reply

With turbo mode disabled (type about:config in the address
bar), Opera uses much less memory and does not seem much
slower.